I thought that it would be a good idea to point out that for `getVisibleElements` to be *truly* generic, this `break` should be changed to `continue`. The way that the viewer currently works (and will work with #2660), this will not be an issue though. I also don't foresee it ever being an issue in this project.

The reason that I didn't make this change is that it will negatively impact the performance of `getVisibleElements` for all documents. It would be particularly bad for longer documents (anything over 100 pages), where the time spent in `getVisibleElements` increased by __at least__ an order of magnitude in my quick testing.